Common questions

What size should redo log be?

author 0

What size should redo log be?

The minimum size permitted for a redo log file is 4 MB. See Also: Your operating system–specific Oracle documentation. The default size of redo log files is operating system dependent.

How do I resize a redo log in standby database?

Following are the steps to drop and create new standby database:

  1. Check Primary Redo Thread Number and size.
  2. Check Standby Thread number and Size for Standby redo logs.
  3. Stop the data-guard recovery process in Standby database:
  4. Drop the existing Standby redo files:
  5. Create new Standby logfile with THREAD Clauses.

How do you improve redo log writing performance?

The steps for tuning redo log performance are straightforward:

  1. Determine the optimal sizing of the log_buffer.
  2. Size online redo logs to control the frequency of log switches and minimize system waits.
  3. Optimize the redo log disk to prevent bottlenecks.

How do you calculate redo size?

You can add up the total number of logs between log switches and divide by total time to obtain a rough estimate of the number of bytes of redo log generation.

How do I know the size of my redo log block?

The easy way to find redo block size is to get trace of redolog and read that.

  1. Below one is done on solaris platform: Dump redolog:
  2. Now check generated trace (it will under the same location where alert log is present)
  3. So redolog block size in this database is of 512 bytes.

What does redo log file contains?

The most crucial structure for recovery operations is the redo log, which consists of two or more preallocated files that store all changes made to the database as they occur. Every instance of an Oracle Database has an associated redo log to protect the database in case of an instance failure.

How do I drop the active redo log group?

To drop a member of an online redo log group use the following command: ALTER DATABASE DROP LOGFILE MEMBER ‘/DISK4/log2b. dbf’; Same statement holds good for OMF, find the logfile member full_path_file_name and drop the member.

How do I check standby for redo logs?

How to identify standby redo logs? SQL> select * from v$logfile where type=’STANDBY’; .

How do I change the redo log size in Oracle 11g?

select group#, status from v$log; You may have to run the alter command up to three times to get group 1 to be CURRENT. Repeat steps 1 to 7 for group 2, group 3, and group 4. Confirm the size change to each group is now 165 Mb.

How do you find the frequency of a redo log switch?

Ideally redo log switch frequency should be 4-5 log switches per hour. If there is frequent log switches then check the size of redo logs and increase accordingly. V$LOG_HISTORY is used to check history of redo log generation in Oracle. V$LOGFILE is used to check the file name and location of redo logs.

What is log file sync waits?

Log file sync waits occur when the LGWR process is unable to complete writes fast enough Redo log activity increases as a function of system activity, and high log file sync waits may occur during periods of high DML activity. …

How to change the size of redo logs?

1. Check Current Redo Logs They are all 50MB. 2. Add 3 Groups with New Size (1GB) Database altered. 6 rows selected. 3. Switch Logfile to New Groups Make some redo log switching until you see Log Writer Process (LGWR) is working on the new redo. System altered. System altered. 6 rows selected.

What are Oracle redo logs?

Redo logs are the most crucial part of the Oracle database. As a part of tuning, you must check the redo log size and switch frequency. For proper functioning of the Oracle database you must avoid frequent log switches. Oracle redo logs consists of two or more pre-allocated files which record all changes made to the database.

What is Oracle redo logfile size advisor?

Oracle has been introducing one utility after the other to ease the life of database administrators. Redo Logfile Size Advisor is a great Oracle 10g advisory utility that helps you determine optimal online redo log file size.

What should be the frequency of redo log switch?

Ideally redo log switch frequency should be 4-5 log switches per hour. If there is frequent log switches then check the size of redo logs and increase accordingly. V$LOG_HISTORY is used to check history of redo log generation in Oracle. V$LOGFILE is used to check the file name and location of redo logs.

author

Back to Top